1. Field of the Invention
This invention relates to fixings for flat roof structures. More particularly the invention concerns the fixing of insulating boards and waterproof sheeting, if required to be fixed with the insulating boards, on a sheet panel forming a cover plate for a flat roof.
2. Description of the related Art
A known form of fixing employs a sleeve which is inserted into a drilled hole leading through the waterproof sheeting, if included, the insulating board and the sheet panel. The lower end of the sleeve projects beyond the sheet panel and includes a part which is expandable so that its outside diameter becomes larger than the drilled hole diameter. This part of the sleeve is expanded by tightening a clamping means which extends through a plate-like or disc-like element and the bore of the sleeve.
A fixing of this form is disclosed in German Utility Model 7,818,691, and consists of a blind rivet, a spacing or distance sleeve and a washer. It is used for fixing insulating boards on a flat, corrugated, meander shaped or trapezoidal sheet panels in roof and wall constructions. The distance sleeve is supported on the inside of the sheet panel and against the underside of a plate-shaped or disc-shaped element which rests on the upper side of the uppermost waterproof sheeting or insulating board, and a blind rivet is used as the clamping and sleeve expanding means. The blind rivet normally consists of a rivet sleeve and rivet pin. By clamping the rivet pin, the rivet-sleeve which projects through the drilled hole in the sheet panel opens out and forms a rivet head for engaging behind the sheet panel.
The length of the blind rivet and especially the length of the distance piece must be adapted to the thickness of the insulating board(s) and possible waterproof sheetings; that is, a certain embodiment of this known fixing device can only be used for a given spacing between the sheet panel and the disc-shaped element, or in other words for a specific thickness of insulating board, including the cover plate for the flat roof. It is also a disadvantage that this known fixing cannot be easily detached again. Therefore, it is desirable for renovation and/or maintenance purpose to provide a fixing device which can be removed so that the less durable insulating and sealing material can be removed and replaced without damaging the sheet panel.